Electrical Resistivity Imaging of a Permanganate Injection During In Situ Treatment of RDX‐Contaminated Groundwater

Abstract

Groundwater beneath the former Nebraska Ordnance Plant (NOP) is contaminated with the explosive hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) and trichloroethene (TCE). Previous treatability experiments confirmed that permanganate could mineralize RDX in NOP aquifer material. The objective of this study was to determine the efficacy of permanganate to transform RDX in the field by monitoring a pilot‐scale in situ chemical oxidation (ISCO) demonstration. In this demonstration, electrical resistivity imaging (ERI) was used to create two‐dimensional (2‐D) images of the test site prior to, during, and after injecting sodium permanganate. The ISCO was performed by using an extraction‐injection well configuration to create a curtain of permanganate. Monitoring wells were positioned downgradient of the injection zone with the intent of capturing the permanganate‐RDX plume. Differencing between ERI taken preinjection and postinjection determined the initial distribution of the injected permanganate. ERI also quantitatively corroborated the hydraulic conductivity distribution across the site. Groundwater samples from 12 downgradient wells and 8 direct‐push profiles did not provide enough data to quantify the distribution and flow of the injected permanganate. ERI, however, showed that the permanganate injection flowed against the regional groundwater gradient and migrated below monitoring well screens. ERI combined with monitoring well samples helped explain the permanganate dynamics in downgradient wells and support the use of ERI as a means of monitoring ISCO injections.

Heterogeneity influences on stream water–groundwater interactions in a gravel-dominated floodplain

“…Additional data were trimmed from A c c e p t e d M a n u s c r i p t 7 the data during the inversion process. The HF method has been utilized successfully within a number of applications published in the peer-reviewed literature (Halihan et al, 2005;Ong et al, 2010;Heeren et al, 2010;Heeren et al, 2011;Keppel et al, 2011;Halihan et al, 2011;Halihan et al, 2012;Christenson et al, 2012;Halihan et al, 2013;Heeren et al, 2014). Miller et al (2014) also demonstrated that the HF method was more suitable for the gravel-dominated alluvial floodplains investigated in this study by comparing the technique to the standard dipoledipole ER array and inversion.…”

In Situ Chemical Oxidation of RDX‐Contaminated Groundwater with Permanganate at the Nebraska Ordnance Plant

“…ERI measurements were also taken at later dates (i.e., 30, 60, and 90 d), but these readings failed to conclusively locate permanganate-treated groundwater. Additional ERI details and results from this study are provided in Halihan et al (2009).…”

The hydraulic conductivity structure of gravel-dominated vadose zones within alluvial floodplains

“…The data acquisition and inversion utilized a proprietary Oklahoma State University method (HF, OSU Office of Intellectual Property, 2004;Halihan et al, 2005) to acquire apparent resistivity data and convert them to a model resistivity profile. The HF method has been utilized successfully within a number of applications published in the peer-reviewed literature (Halihan et al, 2005;Ong et al, 2010;Heeren et al, 2010Heeren et al, , 2011Keppel et al, 2011;Halihan et al, 2011Halihan et al, , 2012Halihan et al, , 2013Christenson et al, 2012;Heeren et al, 2014). The method has even been used and accepted by government agencies, such as the Department of Defense and U.S. EPA.…”